package ch5;

public class Example5_9 {
    public static void main(String args[]) {
        A5_9 a=new A5_9();
        System.out.println("面积："+a.getArea(100));
        a.speak();
    }
}

class A5_9 {
    final double PI=3.1415926;// PI是常量
    public double getArea(final double r) {
        return PI*r*r;
    }
    public final void speak() {
        System.out.println("您好，How's everything here ?");
    }
}

